In a formal complant to the FTC, the groups -- which have complained about the merger of the search company and online marketer and its implications for privacy -- said they learned this week that DoubleClick hired law firm Jones Day to counsel it on antitrust issues related to the merger, currently being reviewed by the FTC. The groups want the FTC to either block the deal of put conditions on it.

According to the Jones Day Web site, "Jones Day is advising DoubleClick Inc., the digital-marketing-technology provider, on the international and U.S. antitrust and competition law aspects of its planned $3.1 billion acquisition by Google Inc. The proposed acquisition will combine DoubleClick's expertise in ad-management technology with Google's internet search and content platform. The transaction is currently under review by the U.S. Federal Trade Commission (FTC) and European Commission. "

The groups pointed out that Majoras once worked as an antitrust attorney for Jones Day, and that her husband, John, is a partner in the firm, saying that represents a clear conflict and that she must recuse herself from the review.

In their filings, the groups pointed out that Majoras has recused herself numerous times from antitrust matters with "similar conflicts," including Procter & Gamble's purchase of Gillette, where Jones Day was representing P&G, and Valero Energy and Premcor because Jones Day represented Valero.

DoubleClick responded in a statement that the firm handling the FTC end of the deal is Simpson Thacher, which it said "has been DoubleClick's outside counsel since July of 2005 and was retained to represent it in all aspects of its proposed acquisition by Google, including with respect to United States antitrust matters.

"From the outset, Simpson Thacher has represented DoubleClick before the Federal Trade Commission and continues in that capacity."

By contrast, it said, "Jones Day has been engaged primarily with respect to European and other non-U.S. jurisdictions. Jones Day was not engaged to represent, and has not represented DoubleClick before the Federal Trade Commission or appeared before the Commission on DoubleClick’s behalf."

According to an FTC spokeswoman, the chairman is currently reviewing the complaint with the agency's chief ethics officer. "We learned on Wednesday that Jones Day is representing DoubleClick before the European Commission, not the FTC," she said, "and Jones Day has not appeared before the FTC in this matter."

Rep. Joe Barton (R-Texas), the generally deregulatory minded ranking member of the House Energy & Commerce Committee and its former chairman, also has privacy concerns about the merger, asking Google Wednesday for answers to a host of questions.